1. Field of the Invention
The present invention relates generally to a hand-written, on-line character recognition apparatus and method and, more particularly, is directed to an evaluation tree scan control apparatus and method for use with a hand-written, on-line character recognition apparatus and method.
2. Description of the Prior Art
In order to understand the present invention more clearly, let us first explain the general principles of stroke order of hand-written Japanese characters. Though there are inevitably a number of exceptions, most Japanese characters are written according to the established principles of stroke order. Generally, hand-written characters are recognized in the following two steps.
1st step: To extract various characteristics from strokes (dot data) of a hand-written character data obtained from a data tablet by a tablet pen.
2nd step: To evaluate the characteristics extracted in the 1st step by comparing them with the characteristics of each character described in a recognition dictionary data base, thereby detecting the character having the best evaluated result.
The recognition dictionary data base used in the 2nd step describes therein characteristics of respective characters as follows.
For example, the Japanese character (KANJI in Japanese) " " describes a characteristic which means a horizontal stroke ".fwdarw.". Further, the Japanese character " " describes a characteristic which means two strokes but in the cursive-style or in the semi-cursive style. This symbol describes a characteristic of ".fwdarw.", " " and ".fwdarw.". In this case, the broken arrow characteristic " " indicates the movement of a pen between the two hand-written strokes. Furthermore, a character " " is written by two strokes but it really describes characteristics of "43 , " and ".dwnarw.". Also in this example, the broken arrow characteristic represents the movement of the pen between two hand-written substrokes. In this case, the description of ".fwdarw." is included in the above-mentioned two Kanji characters " " and " ".
This is also true for Kanji characters having a common portion. Though the above-mentioned Kanji characters " " and " " are simpler and are essentially considered to be single element characters, most Kanji comprise two or more elements. In almost all cases, there is one key element, known as the radical, which indicates the general nature of the character. This radical combines with one or more other elements which give more specific information. For example, the Kanji character " " (meaning "forest" in English) is the combination of the radical " " (meaning "tree" and "wood" in English) and the Kanji character " " (meaning "tree" in English) to provide the meaning of "forest" in English. Further, the Kanji character " " is the combination of radical " " and another element " " (meaning "public," "fair" or "lord" in English) to provide the meaning of "pine" in English.
As described above, though the Kanji characters " " and " " have the common radical " ," they are separately described in the dictionary. Furthermore, there are Kanji characters which allow a plurality of stroke orders when hand-written. Let us consider Kanji when hand-written. For example, let us consider the Kanji character, " " (meaning "right" in English). The Kanji character " " is the combination of the element " " and the element of " " ("mouth" in English) to provide the meaning of "right" in English. In this case, in order to write the Kanji " ," there are two stroke orders. One describes characteristics of ".fwdarw.", " ", ".rarw." and the other describes characteristics ".rarw.", " " and ".fwdarw.". In addition, the characteristics of the Kanji character " " are again described therein.
As described above, though the characteristics described in the prior art dictionary have the common portion, the prior-art dictionary describes the whole characteristics of different Kanji characters in parallel. As a result, since the prior-art dictionary for recognition is constructed as described above, the dictionary has many overlapping portions for Kanji characters and thus, the dictionary is inevitably made large in size.
Further, during evaluation, the common characteristic portion is scanned in a multiplexed fashion, i.e. is scanned a multiple number of times, which increases the time required for recognition.